carbonyl compounds

• What is the boiling point of carbonyl compounds?

  Higher boiling point than alkanes / alkenes but lower boiling point than alcohols / carboxylic acids as they are moderately polar due to permanent dipoles of C=O bond, forming pd-pd interactions
• What is the solubility of carbonyl compounds?

  • Soluble in water as they can form H-bonds with water
  • As Mr increases, solubility decreases due to predominant pd-pd and increase in steric hindrance due to bulky alkyl groups, reducing the extent of H-bonding with water
  • soluble in non-polar solvents
• What is one way to prepare aldehyde?

  Oxidation of primary alcohols
• What is the R&C for oxidation of primary alcohols to aldehydes?

  K2Cr2O7 in dilute H2SO4, heat with immediate distillation
• What is one way to prepare ketones?

  Oxidation of secondary alcohols
• What is the R&C for oxidation of secondary alcohols?

  K2Cr2O7 / KMnO4 in dilute H2SO4, heat under reflux
• What is one way to prepare ketones?

  Oxidative cleavage of alkenes
• What is the R&C for oxidative cleavage of alkenes?

  KMnO4, H2SO4 (aq), heat under reflux
• How many reactions can carbonyl compounds undergo?

  3
• What is the type of reaction involving HCN and carbonyl compounds?

  Nucleophilic addition
• What is the R&C for NA?

  HCN with trace amount of NaOH (aq) / NaCN (aq), cold
• Describe the mechanism for NA of ethanoate.
• What is one reaction aldehydes can undergo?

  Reduction to primary alcohol
• What is one reaction ketones can undergo?

  Reduction
• What is the R&C for the reduction of carbonyl compounds?

  1. LiALH4 in dry ether
  2. NaBH4 in methanolic solution
  3. H2, nickel catalyst, heat under pressure
• What is one reaction aldehydes can undergo?

  Oxidation to carboxylic acids
• What is the R&C for the oxidation of aldehydes?

  K2Cr2O7 / KMnO4 in dilute H2SO4, heat under reflux
• How many chemical tests are there to test for the presence of carbonyl compounds?

  4
• What are the 4 chemical tests?

  1. 2,4-DNPH
  2. Tollen's Reagent
  3. Fehling's Reagent
  4. Iodoform test
• What is the type of reaction involving 2,4-DNPH?

  condensation
• What is the positive observations for the chemical test involving 2,4-DNPH?

  orange ppt
• Write out the chemical equation for the reaction involving methanoate and 2,4-DNPH.
• What is the chemical test to test for all aldehydes?

  Oxidation reaction with Tollen's reagent
• What is the positive observation for the test involving Tollen's reagent?

  Silver mirror or black / grey solid
• What compound, other than carbonyl compound, also gives a positive test result involving Tollen's reagent?

  methanoic acid
• What is the chemical test for all aldehydes except for benzaldehyde?

  oxidation reaction with Fehling's reagent
• What is the positive observation for the test involving Fehling's reagent?

  red-brown ppt of copper (I) oxide
• What is the R&C for Tollen's reagent test?

  Tollen's reagent and warm
• What is the R&C for iodoform test?

  Aqueous iodine in NaOH and warm
• What is the positive observation for the iodoform test?

  pale yellow ppt of CHI3